Google banned almost 800m “bad” adverts from its online ad networks last year as the web giant continued to crack down on advertising fraud.

The figure of 780m was an almost 50% increase on 2014. Google also said that this year would see a major focus on stepping up efforts to fight back against bots – software applications that mimic the behaviour of internet users.

“In 2016, we’re planning updates like further restricting what can be advertised as effective for weight loss, and adding new protections against malware and bots,” said Sridhar Ramaswamy, senior vice president of ads and commerce at Google, in a blog post on Thursday. “We want to make sure all the ads you see are helpful and welcome and we’ll keep fighting to make that a reality.

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The move comes amid rising scrutiny and criticism by advertisers of the actual efficacy of campaigns run across Google’s networks.

The company said that its bad-ad fight in 2015 focused on areas including those that carry malware, promote fake goods or weight-loss scams, or phishing for personal information by financial fraudsters.

“Through a combination of computer algorithms and people at Google reviewing ads, we’re able to block the vast majority of these bad ads before they ever get shown,” Ramaswamy said. “We’ve invested in sophisticated technology and a global team of 1,000-plus people dedicated to fighting bad ads.”

Ramaswamy provided some specific figures about the crackdown in 2015:

Google stopped showing ads on more than 25,000 mobile apps because of policy violations.

The company said it rejected more than 1.4m applications from website and app developers who wanted to run Google ads but not follow policies.

Over 17m ads that misled or tricked people into clicking on them, such as system warnings, were rejected.

More than 10,000 sites and 18,000 accounts were suspended for trying to sell counterfeit goods.

More than 12.5m ads were blocked for breaking Google’s rules on promoting healthcare and medical products.

More than 30,000 sites were banned for making misleading weight-loss claims.